Originally Posted by aokashi
The plant on the right looks suspiciously like mondo grass, which is not an aquatic plant species, you might want to look into that just to save yourself from a dying plant messing up your parameters.
I agree on the species and comments. But ironically, this plant does sometimes last in an aquarium, up to a year or more. And it is rather distinctive. I would leave it (Alex), just watch it and if it starts dying and falling apart, pull it out.